1. Field of the Invention
The present invention relates to a car-mounted equipment of a dedicated short-range communication (hereinafter abbreviated as DSRC) system used for intelligent transport systems (hereinafter referred to as ITS) and, particularly, to a DSRC car-mounted equipment which automatically drives a receiver circuit only when it is necessary to suppress the consumption of an electric power and to a DSRC apparatus using the same.
2. Prior Art
In the DSRC car-mounted equipment used for the ITS, in general, a receiver circuit is maintained driven at all times whenever the vehicle is traveling so that a dedicated short-range communication is readily realized when it is required to make a communication with an on-the-road equipment.
FIG. 6 is a block diagram schematically illustrating a conventional DSRC car-mounted equipment and a peripheral constitution thereof. In FIG. 6, the DSRC car-mounted equipment 1 includes a receiver circuit 3 and a transmitter circuit (not shown) for executing the dedicated short-range communication with an on-the-road equipment 2 installed on a path along which the vehicle travels, and a receiver circuit drive means 4 for driving the receiver circuit 3.
The receiver-circuit drive means 4 in the DSRC car-mounted equipment 1 is connected to a battery 6 through an ignition switch 5. When the ignition switch 5 is turned on, the receiver circuit 3 is driven being served with an electric power from the battery 6 mounted on the vehicle.
When the ignition switch 5 is turned on, the receiver circuit drive means 4 is driven by the battery 6 at all times to supply an electric power to the receiver circuit 3.
FIG. 7 is a block diagram illustrating another prior art.
In FIG. 7, a receiver circuit drive means 4 in a DSRC car-mounted equipment 1 is directly connected to a battery 6A incorporated in the DSRC car-mounted equipment 1 separate from a battery 6 for ignition.
As is widely known, the battery 6A is constituted by a cell that is incorporated, a dry cell or a solar cell system.
In this case, the receiver circuit drive means 4 that is connected to the battery 6A continues to supply an electric power to the receiver circuit 3.
As is well known, a transmitter circuit that is not shown in the DSRC car-mounted equipment 1 is supplied with an electric power only when a request for transmission has occurred.
According to the conventional DSRC car-mounted equipment which is supplied with an electric power from the battery 6 mounted on the car as shown in FIG. 6, the receiver circuit drive means 4 continues to supply the electric power to the receiver circuit 3 when the ignition switch 5 is turned on, arousing a problem in that heat is generated by the receiver circuit 3 and by the receiver circuit drive means 4.
In particular, the DSRC car-mounted equipment is mounted near the dashboard in the room of the vehicle and is subject to be heated when it is irradiated with sunlight, and is generally placed under severe temperature conditions where the temperature may exceed 100.degree. C. Accordingly, heat generated by the receiver circuit 3 and by the receiver circuit drive means 4 creates a serious problem.
Referring to FIG. 7, again, when the electric power is directly supplied from the battery 6A in the DSRC car-mounted equipment 1, the receiver circuit 3 is maintained supplied with the electric power even when it does not at all require the electric power such as when the vehicle is left to stand or when the DSRC car-mounted equipment 1 is carried away, leaving a problem in that the life of the battery 6A is shortened due to the continuous consumption of the electric power.
The present invention was accomplished in order to solve the above-mentioned problems, and its object is to provide a DSRC car-mounted equipment which automatically drives the receiver circuit only when it is necessary to suppress the consumption of the electric power, and a DSRC apparatus using the same.
The present invention is concerned with a DSRC car-mounted equipment for executing a dedicated short-range communication with an on-the-road equipment installed on a path along which the vehicle travels, comprising:
a receiver circuit driven upon being supplied with an electric power from a battery; PA1 a receiver circuit drive means for driving said receiver circuit; and PA1 a drive condition judging means for judging the drive conditions of said receiver circuit drive means; PA1 wherein said drive condition judging means includes: PA1 wherein when said vibration data satisfy predetermined conditions for said reference values, judgement signals for driving said receiver circuit are output to said receiver circuit drive means. PA1 a memory means for storing vibration data over a predetermined period; PA1 a communication end signal-forming means for forming a communication end signal when the communication with the on-the-road equipment has ended; and PA1 a reference value-setting means which reads, from said memory means, the vibration data of just before the communication has started with the on-the-road equipment in response to the communication end signal and operates a reference value, and stores said reference value.
vibration data detecting means for detecting the vibration data of said vehicle; and PA2 vibration data judging means for comparing the vibration data of said vehicle with reference values; and
The invention is further concerned with a DSRC car-mounted equipment, wherein said vibration data is a vibration level, said reference value corresponds to a vibration level of said vehicle under predetermined traveling conditions of said vehicle, and said drive condition judging means outputs a judgement signal when said vibration level is greater than said reference value.
The invention is further concerned with a DSRC car-mounted equipment, wherein said vibration data is a vibration frequency, said reference value corresponds to a vibration frequency band under predetermined traveling conditions of said vehicle, and said drive condition judging means outputs said judgement signal when said vibration frequency represents said reference value.
The invention is further concerned with a DSRC car-mounted equipment, wherein said vibration data include a vibration level and a vibration frequency, said reference value includes a first reference value corresponding to a vibration level under predetermined traveling conditions of said vehicle and a second reference value corresponding to a vibration frequency band under predetermined traveling conditions of said vehicle, and said drive condition judging means outputs said judgement signal when said vibration level is larger than said first reference value and when said vibration frequency represents said second reference value.
The invention is further concerned with a DSRC car-mounted equipment, wherein said vibration data include a vibration level and a vibration frequency, said reference value includes a first reference value corresponding to a vibration level under predetermined traveling conditions of said vehicle and a second reference value corresponding to a vibration frequency band under predetermined traveling conditions of said vehicle, and said drive condition judging means outputs said judgement signal when said vibration level is larger than said first reference value or when said vibration frequency represents said second reference value.
The invention is further concerned with a DSRC car-mounted equipment, wherein said drive condition judging means includes a filter means for filtering said vibration data, and compares the vibration data after filtered with said reference value.
The invention is further concerned with a DSRC car-mounted equipment, wherein said drive condition judging means includes an external input switch, and said reference value is variably set depending upon an operation signal output from said external input switch when said external input switch is operated.
The present invention is further concerned with a DSRC car-mounted equipment, wherein said reference value is set being changed-over to a plurality of steps depending upon said operation signal.
The invention is further concerned with a DSRC car-mounted equipment, wherein said reference value is updated and set based upon the vibration data detected when said external input switch is operated.
The invention is further concerned with a DSRC car-mounted equipment, wherein said drive condition judging means includes a vehicle speed sensor for detecting the speed of said vehicle, and said reference value is variably set depending upon said vehicle speed.
The invention is further concerned with a DSRC car-mounted equipment, wherein said drive condition judging means includes:
The invention is further concerned with a DSRC apparatus using a DSRC car-mounted equipment, comprising a plurality of dents and bumps formed maintaining a predetermined distance and a predetermined width on a predetermined region of the path along which the vehicle travels, wherein said drive condition judging means outputs said judgement signal in response to the result of comparison of a reference value corresponding to said dents and bumps with said vibration data.
The invention is further concerned with a DSRC apparatus, wherein said dents and bumps are formed on a region just preceding a communication region where there is installed an on-the-road equipment with which the communication is executed from the receiver circuit.
The invention is further concerned with a DSRC apparatus, wherein said dents and bumps are formed on a region just preceding a curved region of said traveling path.
The invention is further concerned with a DSRC apparatus, wherein said dents and bumps are formed on a region just preceding a sleep warning region of said traveling path.
The invention is further concerned with a DSRC apparatus, wherein the distance and the width of said dents and bumps are variably set depending upon different regions of said traveling path.